This invention relates to aromatic polyether ketones and a process for their production. More particularly, this invention relates to aromatic polyether ketones having chemical structures wherein phenylene groups are connected at their para positions via ether linkages and ketone linkages, and being characterized by excellent heat resistance, chemical resistance, physical properties and relatively easy processable property, and a process for producing thereof.
Heretofore, the aromatic polyether ether ketone so-called "PEEK" has been already known as one of the typical polymers wherein phenylene groups are connected at their para positions via ether linkages and ketone linkages, which comprises repeating units of the formula: ##STR3## (e.g. T. C. Stening et al., Modern Plastics, November 1981, pp. 86-89).
Furthermore, it has been also known that aromatic polyether ketones comprising repeating units of the formula: ##STR4## wherein ether linkages and ketone linkages are connected at the para positions of phenylene groups mutually. Such aromatic polyether ketones comprising units of the formula (B) can be produced, for example, by Friedel-Crafts reaction of 4-phenoxybenzoyl chloride in the presence of a Lewis acid catalyst such as boron trifluoride, aluminum chloride, etc. (U.S. Pat. Nos. 3,441,538, 3,442,857, 3,953,400, and 4,229,564, British Pat. Nos. 971,227, 1,086,021, 1,102,679 and 1,164,817); or by polycondensation of an alkali metal salt of 4-(p-halogenobenzoyl)phenyl (U.S. Pat. No. 3,634,355 and British Pat. No. 1,153,527); or by polycondensation of a 4,4'-dihalogenobenzophenone and a dialkali metal salt of 4,4'-dihydroxybenzophenone (U.S. Pat. Nos. 4,108,837 and 4,175,175, British Pat. Nos. 1,078,234 and 1,177,183).
Although it has been known that the thus produced aromatic polyether ketones having no substituents on aromatic rings are excellent in heat resistance, chemical resistance and mechanical properties, the melt processing of the polymers has been also known to be undesirably difficult, because they are crystalline polymers having a glass transition point of 154.degree. C. and a melting point as remarkably high as 365.degree.-367.degree. C., and therefore they need extremely high temperature of 400.degree. C. or higher for their melt processing.